The impact of semantic matching on the additive effects of object-based attentional selection

Different types of objects that are overlapped or adjacent in space usually have close semantic relationships in real-world scenes. Previous studies have found that different types of objects can elicit the object-based effects and have confirmed that these object-based effects, which are just overlapped, cannot be additive. However, it is still unclear whether object-based effects induced by different types of objects can be additive if they have a close semantic relationship. Therefore, the purpose of the current study was to investigate whether and how semantic matching affected the additive effects of object-based attention by adopting the variant of the two-rectangle paradigm and simultaneously/solely presenting lexically defined and geometrically defined objects (Experiment 1) or real objects (Experiment 2). We found that space- and object-based effects were observed for different types of stimuli. The difference in the space-based effects among the geometric only, Chinese words only, and semantically mismatched and semantically matched conditions was not significant. However, the object-based effects were larger for the semantically matched condition than those for semantically mismatched, geometric only and Chinese words only conditions, which were not different from one another. These results suggest that different types of objects can not only steadily induce object-based effects, but also give rise to the additive effects of object-based attention depending on whether they have close semantic relationships.